Research and Development of Viscous Fluid Dampers for Improvement of Seismic Resistance of Thermal Power Plants: Part 3 — Evaluation of Vibration Control Performance

Abstract

After Great East Japan Earthquake in 2011, the base load power in Japan was shifted from nuclear power to coal-fired thermal power. Stable electricity supply is one of important infrastructure, so improvement of seismic reliability of coal-fired thermal power plant and related structures is very important. Boiler structures in coal-fired thermal power plants are generally high-rise structures, and boilers in the structures are usually hung on the top of the structures in order not to restrict thermal expansion. Therefore boilers easily vibrate by earthquakes. In order to suppress vibration of boilers during earthquakes, stoppers made of steel are installed between boilers and support structures. The stoppers have simple mechanism and dissipate vibration energy by plastic deformation of steel material. However, further improvement of vibration control performance is required from the viewpoint of above-mentioned social requirements and recent large earthquakes such as the Great East Japan Earthquake, the Kumamoto earthquake in 2016 and so on. This study proposes an application of a damper using viscous fluid to boilers of coal-fired power plants. The damper is set between boilers and support structures. There are many examples of application of the damper using viscous fluid to buildings and civil engineering structures. Therefore the application of the damper to boilers will be effective. In this paper, a seismic response analysis using an analysis model of a boiler structure is conducted. The analysis model has plural stoppers or plural dampers. The response analysis result is evaluated from the viewpoint of vibration control performance. In other words, story shear force of the support structure is evaluated. In addition various limitations such as the maximum stroke of the dampers are taken into account. As a result, story shear force of the support structure with the proposed damper is smaller than that of the structure with the conventional stopper made of steel, so the proposed damper has high vibration control performance.